1. Field of the Invention
This invention generally concerns replaceable refractory parts which come into contact with molten metal in a metallurgical process and, more particularly, to apparatus for minimizing wear on refractory elements such as plates and sleeves of gate valves which handle molten steel, wherein the refractory elements are slowly consumed by wear and need replacement eventually with new elements. The invention specifically concerns an arrangement for retarding the rate of wear of the consumable refractory elements such as refractory plates and sleeves for gate valves.
2. Description of the Prior Art
Pouring ladles for molten metallic material, especially molten steel, have associated maintenance problems in that the gate valves of refractory material provided on such pouring ladles wear out prematurely and need replacement. The problem is especially severe in the case of pouring ladles which are relatively of high capacity and which handle relatively high density molten metal at substantially high temperatures. Refractory gate valve plates, being porous, are infiltrated by molten metal through pores of the exposed surfaces of the gate valve plate. The infiltrating molten metal permeates the exposed refractory material causing it to breakdown. Molten metal also flows into narrow gaps present between precision ground working surfaces of the valve plate and a base plate which is pressed against the valve plate. Owing to the penetration of molten metal and the existing physical pressure between the valve plate and the base plate, the deterioration of the exposed refractory surfaces is accelerated. To alleviate the problem of severe and premature wear of the refractory parts, it is known in prior art to soak and cover the surfaces of the refractory parts with tar, or other hydrocarbon material, before putting the refractory parts into use in gate valves. The tar material would plug the open pores of at least the exposed refractory surfaces and impede the penetration of molten metal into the body of the refractory elements, thereby somewhat lengthening the useful life of the refractory elements. While the soaking treatment of refractory elements with tar would undoubtedly improve the useful life of the refractory elements, the problem still exists that the tar or hydrocarbon layer and material in the pores would be consumed relatively soon by evaporation, thus necessitating repeated and frequent treatment of the refractory elements or members. Repeated treatment of the refractory members with tar or similar material would necessitate an interruption of the operation of the pouring ladle of which the gate valve and the refractory members are a part. As is well known, frequent interruptions in the continuity of operation of the pouring ladle result in wasteful "downtime", thus rendering the entire process very uneconomical.